code: def test_efficiency(self):
      assert nx.efficiency(self.G2, 0, 1) == 1
      assert nx.efficiency(self.G2, 0, 2) == 1 / 2
  
file_path: networkx/networkx/algorithms/tests/test_efficiency.py
imports: import networkx
label_desc: Use image node_id 4 for calling the TestEfficiency obj's underlying member method code with example usage: obj.test_efficiency() without return types